==> Employee.java <==
import java.util.*;

public class Employee
{
   String name;
   float salary;
   Vector subordinates;
   boolean isLeaf;
   Employee parent = null;
//--------------------------------------
   public Employee(String _name, float _salary)
   {
      name = _name;
      salary = _salary;
      subordinates = new Vector();
      isLeaf = false;
   }
   //--------------------------------------
   public Employee(Employee _parent, String _name, float _salary)
   {
      name = _name;
      salary = _salary;
      parent = _parent;
      subordinates = new Vector();
      isLeaf = false;
   }
   //--------------------------------------
   public void setLeaf(boolean b)
   {
      isLeaf = b;    //if true, do not allow children
   }
   //--------------------------------------
   public float getSalary()
   {
      return salary;
   }
   //--------------------------------------
   public String getName()
   {
      return name;
   }
   //--------------------------------------
   public boolean add(Employee e)
   {
      if (! isLeaf) 
         subordinates.addElement(e);   
      return isLeaf;    //false if unsuccessful
   }
   //--------------------------------------
   public void remove(Employee e)
   {
      if (! isLeaf)
         subordinates.removeElement(e);
   }
   //--------------------------------------
   public Enumeration elements()
   {
      return subordinates.elements();
   }
   //--------------------------------------
   public Employee getChild(String s)
     {
        Employee newEmp = null;

        if(getName().equals(s))
           return this;
        else
        {
           boolean found = false;
           Enumeration e = elements();
           while(e.hasMoreElements() && (! found))
           {  
              newEmp = (Employee)e.nextElement();
              found = newEmp.getName().equals(s);
              if (! found)
                 {
                 newEmp = newEmp.getChild(s);
                 found =(newEmp != null);
                 }
           }
           if (found) 
              return newEmp;
           else
              return null;
        }
     }

   //--------------------------------------
   public float getSalaries()
   {
      float sum = salary;
      for(int i = 0; i < subordinates.size(); i++)
      {
         sum += ((Employee)subordinates.elementAt(i)).getSalaries();
      }
      return sum;
   }
}
==> JxFrame.java <==
import java.awt.*;
import java.awt.event.*;
import java.util.*;

//swing classes
import com.sun.java.swing.text.*;
import com.sun.java.swing.*;
import com.sun.java.swing.event.*;


public class JxFrame extends JFrame
{
   public JxFrame(String title)
   {
      super(title);
      setCloseClick();
      setLF();
   }
   private void setCloseClick()
   {
      //create window listener to respond to window close click
      addWindowListener(new WindowAdapter() 
       {
	    public void windowClosing(WindowEvent e) {System.exit(0);}
	    });
   }
   //------------------------------------------
   private void setLF()
   {
   // Force SwingApp to come up in the System L&F
	String laf = UIManager.getSystemLookAndFeelClassName();
	try {
       UIManager.setLookAndFeel(laf);
   	 }
       catch (UnsupportedLookAndFeelException exc) 
         {System.err.println("Warning: UnsupportedLookAndFeel: " + laf);}
       catch (Exception exc) {System.err.println("Error loading " + laf + ": " + exc);
	   }
   }
}
==> RectButton.java <==
import java.awt.*;
import java.awt.event.*;
import java.util.*;

//swing classes
import com.sun.java.swing.text.*;
import com.sun.java.swing.*;
import com.sun.java.swing.event.*;
import com.sun.java.swing.border.*;
import com.sun.java.swing.tree.*;

public class RectButton extends JButton implements Command
{
   Mediator med;

  public RectButton(ActionListener act, Mediator md)
  {
  super("R");
  setBorder(new EmptyBorder(0,0,0,0));
  addActionListener(act);
  med = md;
  }
  public void Execute()
  {
   
  }
  
}

==> empTree.java <==
import java.awt.*;
import java.awt.event.*;
import java.util.*;

//swing classes
import com.sun.java.swing.text.*;
import com.sun.java.swing.*;
import com.sun.java.swing.event.*;
import com.sun.java.swing.border.*;
import com.sun.java.swing.tree.*;


public class empTree extends JxFrame
   implements TreeSelectionListener
{
   Employee boss, marketVP, prodVP;
   Employee salesMgr, advMgr;
   Employee prodMgr, shipMgr;

   JScrollPane sp;
   JPanel treePanel;
   JTree tree;
   DefaultMutableTreeNode troot;
   JLabel cost;
   
   public empTree()
      {
         super("Employee tree");
         makeEmployees();
         setGUI();
      }
   //--------------------------------------
      private void setGUI()
      {
         treePanel = new JPanel();
         getContentPane().add(treePanel);
         treePanel.setLayout(new BorderLayout());
         
         sp = new JScrollPane();
         treePanel.add("Center", sp);
         treePanel.add("South", cost = new JLabel("          "));
         
         treePanel.setBorder(new BevelBorder(BevelBorder.RAISED));
         troot = new DefaultMutableTreeNode(boss.getName());
         tree= new JTree(troot);
         tree.setBackground(Color.lightGray);
         loadTree(boss);
         /* Put the Tree in a scroller. */
         
         sp.getViewport().add(tree);
         setSize(new Dimension(200, 300));
         setVisible(true);

      }
      //------------------------------------
      public void loadTree(Employee topDog)
       {
         DefaultMutableTreeNode troot;
         troot = new DefaultMutableTreeNode(topDog.getName());
         treePanel.remove(tree);
         tree= new JTree(troot);
         tree.addTreeSelectionListener(this);
         sp.getViewport().add(tree);
         
         addNodes(troot, topDog);
         tree.expandRow(0);
         repaint();
      }
      //--------------------------------------
      private void addNodes(DefaultMutableTreeNode pnode, Employee emp)
      {
      DefaultMutableTreeNode node;

      Enumeration e = emp.elements();
        while(e.hasMoreElements())
            {
            Employee newEmp = (Employee)e.nextElement();
            node = new DefaultMutableTreeNode(newEmp.getName());
            pnode.add(node);
            addNodes(node, newEmp);
            }
      }
      //--------------------------------------
      private void makeEmployees()
      {
      boss = new Employee("CEO", 200000);
      boss.add(marketVP = new Employee("Marketing VP", 100000));
      boss.add(prodVP = new Employee("Production VP", 100000));

      marketVP.add(salesMgr = new Employee("Sales Mgr", 50000));
      marketVP.add(advMgr = new Employee("Advt Mgr", 50000));

      for (int i=0; i<5; i++) 
         salesMgr .add(new Employee("Sales "+new Integer(i).toString(), 30000.0F +(float)(Math.random()-0.5)*10000));
      advMgr.add(new Employee("Secy", 20000));

      prodVP.add(prodMgr = new Employee("Prod Mgr", 40000));
      prodVP.add(shipMgr = new Employee("Ship Mgr", 35000));
      for (int i = 0; i < 4; i++)
        prodMgr.add( new Employee("Manuf "+new Integer(i).toString(), 25000.0F +(float)(Math.random()-0.5)*5000));
      for (int i = 0; i < 3; i++)
        shipMgr.add( new Employee("ShipClrk "+new Integer(i).toString(), 20000.0F +(float)(Math.random()-0.5)*5000));
        
      }                            
      //--------------------------------------
      public void valueChanged(TreeSelectionEvent evt)
      {
       TreePath path = evt.getPath();
       String selectedTerm = path.getLastPathComponent().toString();

       Employee emp = boss.getChild(selectedTerm);
       if(emp != null)
          cost.setText(new Float(emp.getSalaries()).toString());
      }
      //--------------------------------------
      static public void main(String argv[])
      {
         new empTree();
      }
}